Quantum Physics
Complete parameterization and parameter-space topology of discrete Wigner representations on $d \times d$ phase space
Lucky K. Antonopoulos and Nicolas C. Menicucci
Toroidal discrete Wigner functions (DWFs) for finite-dimensional systems are non-unique. We completely parameterize and topologically classify the labeled single-qudit ${d\times d}$ representations whose phase-point operators are Hermitian, unit-trace,
Hilbert–Schmidt orthogonal, and Weyl–Heisenberg covariant, determining the independent parameter freedom in every dimension. Our previously established stencil
theorem expresses this family as descents of a doubled ${2d\times2d}$ parent Wigner representation. Here, we solve its projected-stencil admissibility conditions explicitly to obtain the full parameter space of this family. In the
symplectic-
Fourier representation, admissibility fixes the modulus, leaving phase data on a ${d\times d}$ base
cell satisfying a parity-dependent twisted-oddness relation. This gives the parameter space ${(S^1)^{(d^2-1)/2}}$ for odd ${d}$ and ${(S^1)^{(d^2-4)/2}\times\mathbb{Z}_{2}^{3}}$ for even ${d}$. Canonical horizontal and vertical marginals reduce these spaces to ${(S^1)^{(d-1)^2/2}}$ and ${(S^1)^{d\,(d-2)/2}\times\mathbb{Z}_{2}}$, respectively. The same phase data parameterize validity-preserving rephasings of the doubled Weyl–Heisenberg displacement operators. Requiring these operators to have order dividing the
Hilbert-space dimension ${d}$ replaces each ${S^1}$ factor by a discrete ${\mathbb{Z}_{d}}$ factor. The associated
symplectic-
Fourier characteristic functions encode the same operator information, with pointwise magnitudes independent of the valid stencil convention and hence providing convention-independent information about the represented operator within this family. This classification separates the freedom intrinsic to DWF validity from that selected by marginal and displacement-
algebra requirements and makes explicit the structural distinction between odd and even dimensions.
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Quantum Physics
Optimal testing of fermionic and bosonic Gaussian states
Vishnu Iyer, Bryan O'Gorman, Ojas Parekh et al. (+2 more)
We study the problem of property testing
quantum states: given a pure state $|\psi\rangle$ that either (A) belongs to some class $C$ of pure states, or (B) is $\varepsilon$-far in trace distance from all states in $C$, determine which is the case with high probability. It is known that there exists classes $C$ for which the sample complexity of property testing necessarily scales with the size of the system. In this work, we identify classes for which testing only requires a size-independent number of samples. We prove a tight sample complexity of $\Theta(1/\varepsilon^2)$ for the property testing of five important classes of Gaussian
quantum states: 1) Fermionic Gaussian states, 2) Slater determinants, 3) bosonic Gaussian states, 4) zero-mean bosonic Gaussian states, and 5) bosonic coherent states. While property testers for some of these classes have been studied previously, those analyses only gave upper bounds scaling polynomially in the number of modes. In each case, our tester is the projection onto the “top” irrep of two or three copies. We get to constant sample complexity by lower bounding how quickly the rejection probability increases with distance from the class; the main technical component involves bounding the spectral gap of symmetric extension of the test projector. We then establish optimality by proving matching lower bounds based on binary state discrimination for each class. Our testers and optimality claims also extend to the tolerant setting, wherein $\psi$ may be $O(\varepsilon)$-close to $C$ in case (A), rather than lying exactly inside.
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All authors Vishnu Iyer, Bryan O'Gorman, Ojas Parekh, Kevin Thompson, Andrew Zhao
General Relativity and Quantum Cosmology
Second-order multipole response of two nearby incoherent sources in wave-optical imaging of a Schwarzschild black hole
Wenfu Cao, Hongsheng Zhang, Zong-Kuan Guo et al. (+1 more)
We study wave-optical imaging of two nearby, mutually incoherent point sources by a Schwarzschild black hole. Using the spherical-harmonic addition
theorem, we construct partial-wave fields for arbitrary source directions and form images through a finite-aperture
Fourier transform. To isolate the binary structure, we compare the binary image with that of a single source of equal total brightness placed at the brightness centroid. Expanding about the centroid removes the first-order term exactly, so the leading structural correction is controlled by the second central moment, $\mu_2=4a^2q/(1+q)^2$. Numerical calculations confirm the expected dependence of the residual on source half-separation and brightness ratio. We then study its wavelength dependence. At long wavelengths, the imaging kernel varies little across the source separation, making the binary nearly indistinguishable from the centroid reference. As the wavelength decreases, finer fringes enhance the residual, which grows by about a factor of three over $3\leq M\omega\leq12$ ($2.09\geq\lambda/M\geq0.52$), even though the pair remains unresolved in the Rayleigh sense. Meanwhile, the second-order approximation gradually breaks down: its relative error first reaches unity for $17<M\omega<18$ ($0.349<\lambda/M<0.370$), indicating the need for higher-order source moments. These results demonstrate that the distinguishability of a nearby binary is intrinsically chromatic and identify the wavelength range in which the binary is both detectable through its residual and accurately described at second order.
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All authors Wenfu Cao, Hongsheng Zhang, Zong-Kuan Guo, Rong-Gen Cai
Materials Science
Nature of the 175-180 cm$^{-1}$ Raman Feature in Altermagnetic $\alpha$-MnTe
Pankaj Bhardwaj, Rajib Sarkar, Naresh Shyaga et al. (+6 more)
The 175 cm$^{-1}$ Raman mode in $\alpha$-MnTe has long been assigned to the material's only
symmetry-allowed
phonon ($E_{2g}$), yet first-principles calculations consistently place this mode below 100 cm$^{-1}$. Recent works have offered three competing explanations for the discrepancy: a weak
symmetry-lowering ($D_{6h}\rightarrow D_{3h}$)
phonon, an electronic plasmon arising from intrinsic hole self-doping, or an extrinsic MnTe$_2$
impurity signature. Here we resolve this controversy using stoichiometry-controlled molecular beam epitaxy (MBE). We deliberately vary the fraction of pyrite-type MnTe$_2$ secondary phase relative to the $\alpha$-MnTe
matrix. Across this series, the 175 cm$^{-1}$ mode tracks the presence of MnTe$_2$ essentially one-to-one – present wherever MnTe$_2$ is detectable, absent in stoichiometric, single-phase $\alpha$-MnTe at nominal
LASER powers. When
LASER power is ramped up, an additional mode emerges in MnTe as well positioned close to $\approx$ 175 cm$^{-1}$; our detailed temperatures dependendent Raman analysis identifies the
LASER power scorched region close to a distorted MnTe phase, confirmed via transmission electron microscopy. This direct, growth-controlled correlation identifies the mode as an extrinsic MnTe$_2$
impurity signature or as a distorted MnTe feature, rather than an intrinsic
phonon or plasmon feature, providing a practical diagnostic for phase purity in MBE-grown $\alpha$-MnTe and clarifying which Raman features can be reliably attributed to the intrinsic altermagnetic phase.
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All authors Pankaj Bhardwaj, Rajib Sarkar, Naresh Shyaga, Subhransu Kumar Negi, Kartick Biswas, Susmita Jana, Pavan Nukala, B. R. K. Nanda, Dhavala Suri
Instrumentation and Methods for Astrophysics
The Simons Observatory: Design and Initial Performance of the Detector Readout System for the Large-Aperture Telescope
Thomas P. Satterthwaite, Tristan Pinsonneault-Marotte, Shawn W. Henderson et al. (+34 more)
We present the design, implementation, and initial performance of a highly multiplexed cryogenic superconducting detector readout system in the context of its deployment to the Simons Observatory large-aperture
telescope (LAT). The Simons Observatory is a
cosmic microwave background experiment located at 5,200 m in Chile's Atacama Desert. In addition to its 6 m LAT, whose broad range of science goals spans probing large-scale structure to searching for new
Solar System objects, the observatory also currently includes three 0.42 m small-aperture
telescopes, which search for signatures of
primordial gravitational waves. Nearly 100,000 optically-coupled transition-edge sensor bolometers have been deployed across the observatory's four
telescopes to enable these science goals. The readout systems for these
telescopes use microwave frequency multiplexing to simultaneously read out 860 optically-coupled bolometers per transmission line. This is enabled by the large-scale fabrication of multiplexing chips which house
radio-frequency superconducting
quantum interference devices for each detector, and the development of room-temperature electronics to read out these bolometers. This has enabled the largest deployment of superconducting sensors for astronomical observations to date. This paper focuses on the design and implementation of the readout system for the 63,000 detectors in the LAT's cryogenic receiver. We present performance results from an early phase in the
telescope's operation. We show that the readout system's performance enables the instrument to meet key
benchmarks, including successful readout of 81.4% of its optically-coupled bolometers, which exceeds projections, and readout noise-equivalent current consistent with pre-deployment specifications.
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All authors Thomas P. Satterthwaite, Tristan Pinsonneault-Marotte, Shawn W. Henderson, Zeeshan Ahmed, Kam Arnold, Declan Baker, Andrew Bazarko, Josh Borrow, Michael L. Brown, Mark Devlin, Simon Dicker, Peter N. Dow, Shannon M. Duff, Daniel Dutcher, John C. Groh, Saianeesh K. Haridas, Kathleen Harrington, Erin Healy, Johannes Hubmayr, Bradley R. Johnson, Brian Keating, Anna M. Kofman, Adrian T. Lee, Alex Manduca, Aashrita Mangu, Jenna E. Moore, Michael D. Niemack, Sandra O'Neill, John Orlowski-Scherer, Yudai Seino, Mufan Shao, Carlos Sierra, Max Silva-Feaver, Suzanne Staggs, Eve M. Vavagiakis, Yuhan Wang, Edward J. Wollack
Materials Science
Three-Dimensional Topology from Stacking-Controlled Umklapp Scattering in Large-Angle Twisted Graphite
Juncheng Li, Cong Chen and Wang Yao
Large-angle twisted
graphene lies beyond the local-stacking description of conventional moiré systems: inequivalent rotation centers define distinct commensurate interfaces whose low-energy interlayer hybridization is governed by intervalley Umklapp tunneling. For three-dimensional twisted graphite assembled from interfaces with different crystalline
symmetries, a
symmetry-constrained effective model reveals that competition between nonchiral and
chiral tunneling produces one-ring and two-ring nodal-line phases and a $C_3$-protected higher-order topological
insulator in the presence of sublattice (
chiral)
symmetry. The nodal rings carry integer winding numbers, allowing oppositely wound rings to annihilate into the gapped phase. We further examine how sublattice-
symmetry breaking modifies these phases. Density functional theory (DFT) and atomistic calculations for $21.8^\circ$ twisted graphite identify the
equilibrium structure as a higher-order topological
insulator, while compression drives it into a topological Weyl semimetal phase. These findings establish the stacking sequence of
symmetry-inequivalent interfaces as a means of engineering band
topology in three-dimensional twisted structures.
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Quantum Physics
Quantum circuit compilation with constant overhead
Chenyi Zhang, Xinyu Tan, Robin Kothari et al. (+2 more)
Compiling a continuous gate set to a discrete universal gate set generally incurs an overhead. A
circuit composed of $G$ arbitrary one- and two-
qubit gates can be $\epsilon$-approximated by a sequence of gates from $\{H,T,\mathrm{CNOT}\}$ by replacing each original gate by a sequence of $O(\log(G/\epsilon))$ elementary gates. We show that this overhead can be avoided using adaptivity for
polynomial-sized
circuits with inverse-
polynomial target error, which is optimal.
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All authors Chenyi Zhang, Xinyu Tan, Robin Kothari, David Gosset, Craig Gidney
Chemical Physics
A strategic roadmap for an atomistic machine-learning ecosystem
Jörg Behler, Michele Ceriotti, Cecilia Clementi et al. (+47 more)
Data-driven machine learning (ML) techniques have become an essential tool in many domains of science. Their application to atomistic simulations of matter is particularly widespread and impactful. This success is due largely to the existence of a well-developed and established physics-based modeling framework, ranging from first-principles electronic-structure calculations to molecular dynamics and statistical sampling, into which ML was integrated naturally to reshape long-standing trade-offs between accuracy, efficiency, and scale. Nevertheless, this integration raises both conceptual and practical challenges, from choosing between data-centric and physics-based modeling approaches to adapting established software stacks to modern hardware accelerators and ML libraries. As the field evolves rapidly, fueled in part by widespread enthusiasm but also by tangible impact, it seems appropriate to take a moment to consider the current state of the art and open challenges, and reflect on what can be done to better coordinate efforts across the community. With this goal in mind, several members of this community met in Lausanne in January 2026 at CECAM to discuss
algorithms, models, software and hardware infrastructure, and the most promising scientific applications that have become possible thanks to the use of artificial intelligence in atomic-scale simulations. This strategic roadmap paper summarizes the outcomes of these discussions, suggesting some long-term goals, and some concrete actions, to establish a healthy, sustainable and impactful atomistic ML ecosystem.
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All authors Jörg Behler, Michele Ceriotti, Cecilia Clementi, Gábor Csányi, Alin-Marin Elena, Aditi Krishnapriyan, Joseph W. Abbott, Fabio Affinito, Albert P. Bartók, Ilyes Batatia, Filippo Bigi, Florian N. Brünig, Yannick Calvino Alonso, Giuseppe Carleo, Aurélie Champagne, Stefan Chmiela, Marc L. Descoteaux, Ralf Drautz, Alexandra Farcas, Meng Gao, Rohit Goswami, Michael F. Herbst, Christian Holm, James R. Kermode, Alexander L. M. Knoll, Tobias Kreiman, Marcel F. Langer, Hoang-Thien Luu, Yury Lysogorskiy, Mihai-Cosmin Marinica, Rocco Meli, Klaus-Robert Müller, Frank Noé, Mohamadhosein Nosratjoo, Simon Olsson, Christoph Ortner, Aldo S. Pasos-Trejo, Anyang Peng, Eric Qu, Andrea Rizzi, Mariana Rossi, Bassem Sboui, Gregor N. C. Simm, Alexandre Tkatchenko, Jacopo Venturin, O. Anatole von Lilienfeld, William C. Witt, Brandon M. Wood, Tigany Zarrouk, Fabian Zills
General Relativity and Quantum Cosmology
Primordial Tensor Signatures and Gravitational Wave Constraints in Lorentz Violating Inflation with Non-Canonical Kinetics
Dibash Plaban Kalita and Shreya Banerjee
We investigate
primordial tensor perturbations in a Lorentz violating inflationary framework with non-canonical scalar field dynamics. Using an Einstein-Æther type with a higher order kinetic term $K_3X^2$, we derive the tensor propagation speed and its dependence on an effective Lorentz violating coupling. We consider an analytically tractable potential free background and study two representative couplings, $q_k=\lambda_T\phi_k^2$ and $q_k=\lambda_T\phi_k^4$. The resulting tensor spectral index $n_T$ and its running $\alpha_T$ satisfy distinct consistency relations, providing potential signatures of Lorentz violation in the
primordial gravitational wave spectrum. We derive corresponding constraints from the tensor tilt and running and compare them with the stringent late-time bound on the gravitational wave speed from GW170817/GRB170817A. We emphasize that translating this bound into
primordial constraint requires an assumption about the
evolution of tensor sector coupling between inflation and the late Universe. Our results demonstrate that
primordial tensor observables can provide a complementary probe of Lorentz violation and its interplay with non-canonical inflationary dynamics.
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High Energy Physics (Theory)
Complex Phase Structure of Kerr-AdS$_5$ Black Holes: Critical Saddles and Fisher Zeros
Bum-Hoon Lee, Hocheol Lee and Somyadip Thakur
We study the complex saddle structure of singly rotating Kerr–AdS$_5$ black holes using a two-variable reduced model in the grand canonical ensemble at fixed angular velocity, $\Omega$. The small and large black hole saddles merge at a critical point where one Takagi singular value of the complex Hessian vanishes, identifying the soft mode associated with the merger. This merger remains distinct from the Hawking–Page transition throughout the physical domain $|\Omega| < 1$. For the reduced integral with the standard measure, we show that thermal AdS dominates uniformly in a complex neighborhood of each real merger point when Newton's constant $G$ is sufficiently small. Consequently, this neighborhood contains no zeros of the partition function, even though the local saddle merger is described by Airy-type behavior. The Fisher zeros instead accumulate near the Hawking–Page coexistence line, with spacing of order $G$, through interference between thermal AdS and the large black hole saddle. We also show that the real quasi-Euclidean Kerr–AdS$_5$ family satisfies a strict asymptotic Kontsevich–Segal–Witten (KSW) phase bound for $|\Omega| < 1$, with the merger point lying inside the allowed domain. In the fixed angular momentum extended ensemble, two such merger points combine into a cusp with a contour-dependent Pearcey approximation. These results distinguish local saddle degeneracies from global phase coexistence and clarify the different roles of Takagi modes, phase transitions, and zeros of the partition function in the complex black hole saddle structure.
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Quantum Physics
Engineered Dissipation for Thermal-State Tracking Across Quantum Criticality
Saikat Mistry, Dibyajyoti Sahu and Suhas Gangadharaiah
Engineering dissipation has emerged as a powerful strategy for controlling
quantum many-body dynamics, complementing purely coherent control for state preparation. However, finite-time driving across a
quantum critical point generates nonadiabatic excitations and coherences, and existing dissipation-engineering approaches have largely characterized how a fixed environment modifies critical dynamics rather than actively steering a system toward a prescribed thermal trajectory. Here we develop a Markovian dissipative framework for finite-time thermal-state tracking based on engineered population currents with non-negative transition rates, and apply it to the transverse-field Ising model driven across its
quantum critical point. Compared with
unitary dynamics and a natural thermal bath, the engineered dynamics strongly suppresses thermal excitation deviations and provides additional control over coherence damping through a free common current $Q_k$, while exhibiting a substantially steeper residual scaling, $\delta n_{\mathrm{ex}}^{\mathrm{th}}\sim(v/v_{\mathrm{ch}})^2$, than the Kibble–Zurek behavior recovered for
unitary evolution. These results point toward engineered dissipation as a route for controlling thermal-state preparation in driven
quantum critical systems.
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Materials Science
Operando Charge Carrier Dynamics by Intensity-Modulated Photoluminescence: From Perovskite Thin Films to Solar Cells
Constantin Bach, Dong Won Kim, Yitian Du et al. (+2 more)
The charge-carrier lifetime in halide perovskites often varies by orders of magnitude with the injection level, complicating the analysis of conventional time-resolved photoluminescence and comparisons of reported lifetimes. We use intensity-modulated photoluminescence spectroscopy (IMPLS) as a frequency-domain alternative. Carried out under operating conditions, it yields the lifetime at a specific injection level, e.g., one-sun-equivalent illumination. On thin films, IMPLS and steady-state photoluminescence yield comparable lifetimes. For perovskite/transport-layer stacks, the IMPLS response becomes more complex. A dedicated transfer function disentangles charge transfer from interface recombination and predicts an upper limit on the charge-carrier lifetime in the
solar cell. In devices, electrical methods such as intensity-modulated photovoltage spectroscopy (IMVS) often fail to measure the lifetime due to capacitive effects. IMPLS shows not only the same two characteristic frequencies as IMVS, but also a third one, thereby resolving the lifetime itself.
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All authors Constantin Bach, Dong Won Kim, Yitian Du, Yana Vaynzof, Carsten Deibel
Chemical Physics
Autocata: Reaction-network-guided autonomous catalyst screening via capability-centric AI
Ruili Li, Rui Qi, Qingqing Mao et al. (+3 more)
Artificial intelligence (AI) has expanded the accessible space for catalyst discovery, yet executing complex screening campaigns still requires constant human intervention to bridge high-level reaction objectives with underlying computational pipelines. Here, we present Autocata, a knowledge-embedded autonomous
agent that scales catalytic expertise by encoding multistep reaction pathways into reusable,
language-invocable capabilities. Powered by a
Transformer pretrained on two million catalyst-adsorbate structures, the system incorporates a capability registry of 79 adsorbate-specialized generative models spanning complex reaction networks across carbon, nitrogen, oxygen, and hydrogen intermediates. Given a high-level natural-
language prompt, Autocata deconstructs reaction networks, queries and configures matching generative models, generates candidate surface configurations, enforces physical and
geometric validity filtering, and coordinates machine-learning potentials evaluations to rank promising materials. Crucially, the
agent adaptively reconfigures workflows when encountering capability boundaries or task bottlenecks. We demonstrate these capabilities across CH4 activation, nitrogen reduction reaction (N2RR), and CO2-to-methanol pathways. By shifting from static toolkits to an adaptive,
language-driven computational infrastructure, Autocata lowers the barrier for expert-level catalyst discovery and offers a scalable paradigm for self-driving catalytic research.
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All authors Ruili Li, Rui Qi, Qingqing Mao, Ritankar Das, Beien Zhu, Yi Gao
High Energy Astrophysical Phenomena
Improved Population and EOS Joint Inference for Binary Neutron Star Systems
Marc Ebiri and Richard O'Shaughnessy
The extreme environment within
neutron stars presents the opportunity to probe the
nuclear equation of state at high densities while studying the properties of these
stellar remnants. Historically, the equation of state and
neutron star mass distribution have been inferred separately, with the latter often simply assumed to be fixed in studies of the former, but the dependence of the equation of state on
neutron star mass indicates they should be inferred together. In this work, we extend the generalized version of the popular RIFT
algorithm known as Hyperpipe to interface with flexible, user-provided priors that will facilitate joint inference of equation of state and binary
neutron star population hyperparameters. We demonstrate this framework's utility via application to a combination of several existing observations, particularly including massive
galactic pulsars, double
neutron star systems, millisecond X-ray
pulsars, the gravitational wave event GW170817 and the
nuclear symmetry energy, within the context of a widely-adopted parametric EOS family and a simple Gaussian population model. We recover parameters consistent with previous analyses of the EOS and binary
neutron star population, finding the latter to fit a bivariate normal distribution with mean $(\mu_1,\mu_2) = (1.39,1.27) M_{\odot}$ and width $\sigma = 0.08 M_{\odot}$. Furthermore, we implement novel coordinate transformations in our pipeline, with which we have discovered that the ad hoc prior boundaries used for this EOS family may be too restrictive. We present results with relaxed yet still physical prior boundaries, noting vastly improved hyperparameter posteriors and modestly different equation of state inferences.
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Computational Physics · Cross-listed from math.NA
Structure-preserving Fourier Neural Operators for Long-time Cahn-Hilliard Dynamics under Coarse Temporal Supervision
Yingli Li and Y.C. Zhou
Accurate long-time prediction of Cahn-Hilliard dynamics, particularly in the late-stage coarsening regime, is computationally demanding because it requires simulations over extended physical time. Various machine learning approaches have been developed to speed up the simulations through efficient surrogate evaluations. While the learned map can be accurate over a single learned interval, small prediction error will accumulate when the map is repeatedly applied in a long-time prediction, leading to large numerical errors. In this work, we identify the structure function for the coarsening dynamics of the Cahn-Hilliard equation and propose a two-stage structure-preserving
Fourier Neural Operator (FNO) learning framework. Stage~I introduces a bound-conforming FNO (bcFNO) with a soft, magnitude-dependent amplitude penalty. Stage~II retains the bound-conforming objective and supplements it with structure-function regularization, yielding a structure-preserving FNO (spFNO) that corrects late-stage coarsening statistics. Numerical experiments on the various spatial resolutions and reference-solver time steps suggest that the bcFNO stabilizes the long-time prediction by suppressing large amplitude excursions, without changing the low online cost of the FNO. Furthermore, the structure-function term consistently reduces discrepancies in the normalized structure function and provides further correction in associated late-stage coarsening quantities, including the $L^3(t)$ growth trend and the scaling collapse. These results indicate that our multi-stage implementation of physical principles in operator learning could be applied to other multiscale systems with statistical scaling, such as the functionalized Cahn–Hilliard equations and
turbulence, provided that the state constraints and statistical observables are adapted to the governing dynamics.
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Quantum Physics
Fixed-Point Bifurcations and Path-Information Bounds in Nonlinear Exceptional-Point Sensing
Xue-Hao Yu and Cong-Feng Qiao
Nonlinear exceptional points (NEPs) were proposed to circumvent the noise–responsivity cancellation that limits linear exceptional-point sensors. At an NEP, the stationary frequency response can be singular while the
Hamiltonian Petermann factor remains finite, suggesting a genuine signal-to-noise ratio (SNR) enhancement. Yet recent model-specific analyses of nonlinear fluctuations have reached conflicting conclusions. We prove that any singular stationary frequency response requires a fixed-point bifurcation of the nonlinear dynamics. In local fluctuation regimes, the singularities in responsivity and long-time frequency uncertainty are both set by the critical relaxation rate, leading to exact cancellation in the SNR and precluding any divergent enhancement. Furthermore, we derive a path-information bound that applies across both local and nonlinear fluctuation regimes and places a finite ceiling on the long-time SNR enhancement. Notably, this upper bound is attainable in the local fluctuation regime, implying that frequency readout under such parameter settings is information-optimal.
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Quantum Physics
Provable Classical and Quantum Local Algorithms for Max-$k$-Cut and Quantum Advantage at Moderate Girth
Anuj Apte, Abid Khan, Edward Farhi et al. (+3 more)
Broadening the study of
quantum optimization
algorithms from binary to $k$-element alphabets has been shown to open new avenues for potential
quantum advantage. A
quantum advantage claim for approximate optimization requires showing that, under the same assumptions, an efficient
quantum algorithm provably achieves a better performance than can be proven for the best known efficient classical
algorithms. We study local classical and
quantum algorithms for Max-$k$-Cut on $d$-regular graphs of girth $g$. We advance classical
algorithms for this problem by developing a local vector
algorithm based on the explicit vector construction of Thompson, Parekh, and Marwaha (TPM). Our
algorithm gives the best provable cut fraction guarantee among known efficient classical
algorithms on regular graphs for $k\geq3$. To evaluate the performance of QAOA under identical assumptions of girth and regularity, we develop tensor network techniques for general $d$ and $k \geq 2$. In addition, using an equivalence to a coupled qudit–
boson system, we compute the QAOA performance in the infinite-degree limit. Together, these techniques give provable guarantees on QAOA performance on large graphs. Despite the improvements we introduce to the classical
algorithm, QAOA achieves a better cut fraction guarantee for depths $p\geq 9$, corresponding to girth $g\geq 20$, for both finite- and infinite-degree regimes. Thus, we obtain an apparent
quantum advantage from applying QAOA to the Max-$k$-Cut problem.
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All authors Anuj Apte, Abid Khan, Edward Farhi, Kunal Marwaha, Sami Boulebnane, Ruslan Shaydulin
Computational Physics
The Ganglion Network Model: Evolving Trapped Phases in Porous Media
Yashar Mehmani
Partially miscible ganglia trapped within porous media, spanning one or multiple pores and evolving through diffusive mass transfer, are common in subsurface (e.g., CO$_2$ and H$_2$ storage) and manufacturing (e.g., fuel
cells) applications. We present the ganglion network model (GNM), a reduced-order method for simulating how a population of such ganglia evolves inside an arbitrary porous microstructure. GNM operates on a tree graph, the ganglion network, extracted from the pore-scale image of a given sample. Each point on the graph encodes a possible ganglion configuration in the void space, without any loss of
geometric or topological complexity. The
evolution of a population is modeled by representing each ganglion as a particle on the graph and tracking it according to a set of rules formulated herein. The rules capture capillary events such as pore invasion, retraction, snap-off, fragmentation, and merger. Unlike pore-network models, another graph-based modeling tool at the pore scale, GNM solves no system of equations and its cost scales with ganglion count, not domain size. We validate GNM against an image-based pore-network model in 2.5D and 3D domains with populations undergoing ripening, dissolution, and growth. We find good agreement in ganglion statistics, aggregate properties, and spatial configuration. We further argue that the ganglion network is the statistical space needed for extending kinetic theories of Ostwald ripening from single- to multi-pore ganglia, and provide an outline for how to do this. GNM opens the door to modeling other dynamics of trapped phases in porous media.
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Astrophysics of Galaxies
Stacked strong and weak lensing united: Improved measurement of the stellar and dark matter distributions in massive early-type galaxies at $z\sim 0.5$
Momoka Fujikawa and Masamune Oguri
We present a new measurement of the
stellar and dark matter distributions in massive early-type
galaxies at
redshift $0.4<z<0.6$ by combining stacked strong and weak
lensing measurements. The stacked weak
lensing measurements down to the small radius of $0.013\,\mathrm{Mpc}/h$ enabled by the Subaru
Telescope Hyper Suprime-Cam data are combined with stacked enclosed projected mass measurements from 13 strong lens systems. We find that adding strong
lensing constraints improves constraints on the
stellar and dark matter distributions. The central dark matter profile is found to be consistent with the standard Navarro-Frenk-White density profile. The
stellar initial mass function is found to be bottom-heavy. The total density profile in the inner region is described well by the power-law density profile with the slope of $-1.96\pm 0.07$, which can also explain weak
lensing signals out to $1\,\mathrm{Mpc}/h$ reasonably well. The stacked weak
lensing profile constrains an internal mass-sheet transformation parameter to $\lambda_{\mathrm{c}}=0.978\pm0.010$. Our analysis demonstrates that the combination of the stacked strong and weak
lensing serves as a powerful tool for studying central density profiles of
galaxies.
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Cosmology and Nongalactic Astrophysics
Metastable Dark Energy on the Phantom Brane
Purba Mukherjee, Arman Shafieloo, Varun Sahni et al. (+1 more)
Recent DESI observations hint at a preference for dynamical dark energy with an equation of state (EoS) that crosses the phantom divide at $w=-1$. In this work, we investigate metastable dark energy (DE) on the minimal phantom brane. Braneworld effects lead to $w < -1$ at early times, whereas metastable decay of DE results in $w > -1$ at late times. We consider three metastable decay prescriptions on the phantom brane: an exponentially decaying DE component (M1), decay of DE into non-baryonic dark matter (M2), and decay into dark radiation (M3). Using CMB observations, DESI DR2 BAO measurements, and the DES-Dovekie Type Ia
supernova sample, we compare these models with $\Lambda$CDM, the Chevallier–Polarski–Linder (CPL) parametrization, and the minimal phantom-brane model with a non-decaying $\Lambda$. We find that metastable models on the brane are preferred over $\Lambda$CDM, their decay rates being $\Gamma/H_0=0.362\pm0.086$, $0.539\pm0.125$, and $0.483\pm0.112$ for M1, M2, and M3, respectively. Best fits of metastable models improve over $\Lambda$CDM by $\Delta\chi^2_{\rm MAP}=-17.14$, $-18.76$, and $-18.22$, while the corresponding $\Delta{\rm DIC}$ values are $-8.66$, $-9.63$, and $-6.56$. Braneworld screening drives effective phantom behaviour at $z\gtrsim0.4$, while DE decay drives the EoS toward non-phantom values closer to the present epoch, with the phantom divide $w=-1$ being crossed at $z \simeq 0.3$–$0.4$. These results show that the interplay between metastable decay and phantom-brane screening provides a simple physical mechanism for an effective crossing of the phantom divide consistent with DESI observations.
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All authors Purba Mukherjee, Arman Shafieloo, Varun Sahni, Yuri Shtanov
Astrophysics of Galaxies
The "Fork" Geometry in the DESI Main Survey DR1: Implications of Target Selection for Galaxy Evolution Studies
A. Nigoche-Netro, P. Lagos, R. J. Diaz et al. (+3 more)
The Dark Energy Spectroscopic Instrument (DESI) Main Survey Data Release 1 (DR1) provides an unprecedented spectroscopic view of
galaxies and
quasars across a large fraction of the observable Universe. However, the survey's tracer-dependent targeting strategy introduces complex observational selection effects that strongly influence the apparent distribution of
galaxies in the
redshift-luminosity plane. In this work, we investigate the origin of the characteristic "fork" geometry observed in DESI DR1 and show that the observed distribution is consistent with an interpretation in which it arises from the combined action of intrinsic
galaxy bimodality and the survey's
redshift-dependent selection function. We show that the observed underdensity separating the dominant
galaxy populations is influenced not only by the physical Green Valley but also by survey selection effects, since it is further shaped by magnitude limits, surface-brightness selection, and structural incompleteness. Using DESI DR1 spectroscopy together with Legacy Survey photometry, we analyze the roles of the BGS, LRG, ELG, and QSO target classes in producing the observed distribution and assess their impact on luminosity-function measurements. Our results indicate that both target selection and observational biases significantly affect the observed
galaxy distribution and the evolutionary trends inferred from it. We summarize practical observational considerations aimed at minimizing these effects and enabling more robust studies of
galaxy evolution with DESI.
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All authors A. Nigoche-Netro, P. Lagos, R. J. Diaz, E. García-Manzanárez, J. A. Quezada-Pérez, R. Ibarra-Nuño
High Energy Physics (Phenomenology)
Resummation of threshold double logarithms in gluon fragmentation into $^1S_0^{[1,8]}$ quarkonia
Hee Sok Chung
I investigate the threshold double logarithmic behavior of the fragmentation function of a
gluon into $^1S_0^{[1,8]}$ quarkonia, which is suppressed by $1/N$ in Mellin space. While threshold double logarithms have been resummed to all orders in the strong coupling for
gluon fragmentation functions for quarkonia at leading power in $1/N$, it has not been known how to resum them for channels suppressed by powers of $1/N$. Threshold resummation can be important for the $^1S_0^{[1,8]}$ channels, as the tree-level
gluon fragmentation functions have finite yet nonzero values at the kinematical threshold. I derive a formalism for resumming the threshold double logarithms for these channels at the leading double logarithmic level and discuss the phenomenological impact.
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Quantum Physics
Entropy threshold: A simple proxy for performance of quantum error correction
Diego Ruiz and Aleksander Kubica
The rapidly growing landscape of
quantum error-correction (QEC) protocols has produced a wealth of numerical data, but comparatively few heuristics for understanding and predicting their performance. Here, we develop a simple
entropy-based proxy that predicts the thresholds of a variety of QEC protocols, ranging from the code-capacity setting of Clifford-deformed surface codes with biased Pauli or erasure noise to the
circuit-level noise model of the surface or color codes with flag
qubits. Our proxy estimates the threshold by locally comparing the noise
entropy with the error information gained via stabilizer measurements (or spacetime detectors and flag outcomes in the
circuit-level settings). Despite neglecting correlations between stabilizer outcomes and the contribution from code degeneracy, the proxy captures the main trends across diverse settings and yields threshold estimates in good agreement with numerical results. Our work develops much-needed phenomenology that enables simple back-of-the-envelope estimates of QEC performance, recovering and providing an explanation for the results of computationally intensive detailed simulations.
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Physics and Society
Social comparison shapes the evolution of cooperation in structured populations
Xiaojin Xiong, Qin Li, Jurgen Kurths et al. (+2 more)
Human cooperation unfolds in social environments where individuals influence each other through payoff-based learning and social comparison, the tendency to evaluate fitness relative to others. However, it is still unclear how social comparison and population structure jointly shape cooperation. Here, we incorporate social comparison theory into evolutionary dynamics on structured populations, letting fitness depend on individual and neighbour payoffs weighted by a comparison parameter. Under weak selection, we derive conditions favoring cooperation and find that the proposed comparison nonlinearly reshapes the critical benefit-to-cost ratio. Even one individual applying this protocol can affect the population, especially in heterogeneous networks. When comparison tendencies vary, the full distribution, not just the mean, determines evolutionary outcomes. Using a swarm-intelligence-based framework across typical and empirical networks, we identify cooperation-maximizing patterns: optimal states exhibit heterogeneous comparison tendencies, yet collectively align toward assimilative development. These results provide a basis for designing social incentives that harness comparison to promote collective cooperation in human groups.
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All authors Xiaojin Xiong, Qin Li, Jurgen Kurths, Attila Szolnoki, Minyu Feng
Medical Physics
An Uncertainty-Guided Digital Twin Framework for Online Adaptive Proton Therapy in Head and Neck Cancer: A Feasibility Study
Yizhou Wu, Ryan J. Sanford, Huiqiao Xie et al. (+12 more)
Objective: Head and neck (HN)
proton therapy spans six to seven weeks of anatomical change, while offline replanning takes about a week. We present an uncertainty-guided digital twin (UGDT) framework that forecasts treatment-day anatomy before treatment and evaluate whether it generates online adaptive
proton therapy (APT) plans of clinical quality. Approach: A library of 302 longitudinal deformations from 88 previously treated HN patients was transported onto each new patient's treatment planning CT (TPCT) using two-step multi-atlas deformable image registration (DIR) built on a pretrained CT foundation model, generating about 284 predicted CTs (pdCTs) with contours per patient. Dispersion of propagated clinical target volume (CTV) contours defined a patient-specific robust margin. In ten patients, the quality assurance CT (QACT) triggering a replan represented treatment-day anatomy, and the physician-approved replan was the baseline. The pdCT most similar to the QACT (pdCT-H) and one from the lowest quartile (pdCT-L) were planned to within about 5% of baseline plan quality, forward-calculated on the QACT, and reoptimized to generate online APT plans. Main results: pdCT plans scored within -0.7% (pdCT-H) and -1.0% (pdCT-L) of baseline. Forward calculation on QACT reduced high-dose CTV D98% to 88.3% and 85.5%. After online reoptimization, D98% recovered to 98.3 +/- 0.3% and 98.2 +/- 0.3%, versus 98.5 +/- 0.4% at baseline. Spinal cord and brainstem doses remained below tolerance, and plan quality scores were within -1.1% (p = 0.19) and -1.7% (p = 0.01) of baseline. Significance: UGDT generated online APT plans comparable in quality to physician-approved offline replans using anatomy forecast before treatment, enabling a transition from reactive offline replanning toward anticipatory online adaptation.
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All authors Yizhou Wu, Ryan J. Sanford, Huiqiao Xie, Jie Ding, Shupeng Chen, Tung-Ho Wu, Ping-Hsiu Wu, Justin Roper, Jun Zhou, Minglei Kang, Bill Stokes, Sibo Tian, David S. Yu, Xiaofeng Yang, Chih-Wei Chang
Chemical Physics
An atom-based machine-learned dipole-moment model and application to conjugated systems
Yuansheng Zhao, Tamio Yamazaki, Ryohei Hosoya et al. (+2 more)
We introduce a method for predicting the dipole moments of molecular systems by systematically decomposing the total dipole moment into the sum of atomic contributions using the wavefunction from density-functional-theory calculations, and then use graph neutral networks to predict this effective atomic dipole moment from input atomic structure. It is demonstrated that the dipole moments and dielectric function can be accurately predicted even for complicated conjugated systems where the previous bond-based model [Phys. Rev. B 110, 165159] fails. The inference cost of our model scales linearly with the number of atoms and is about 3 times faster compared with Born-effective-charge-based schemes, but shows similar or better accuracy for dielectric function at terahertz range.
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All authors Yuansheng Zhao, Tamio Yamazaki, Ryohei Hosoya, Yu-ichiro Matsushita, Shinji Tsuneyuki
Quantum Physics
Constant Rate Codes with Fully Addressable Transversal T: Good Codes, Sparse Checks
Alexander Meiburg
Recent work by Wills constructed codes with constant rate and transversal $T$. Extending this line of work, we construct asymptotically good CSS codes with fully addressable transversal $T$, permitting selective control over which logical
qubits receive a $T$ gate. We also give Pauli-LDPC codes with transversal $T$ and growing distance at vanishing rate; and a protected-subsystem construction with fully addressable transversal $T$, constant protected rate, distance $\Omega(\sqrt n)$, and sparse (non-Pauli) checks. More generally, we obtain asymptotically good binary codes with full transversal addressability for every fixed finite-order one-
qubit gate, retaining CSS realizations for dyadic phase gates such as $\sqrt T$ and using generally nonadditive codes for rotations such as $R_z(\pi/7)$. The remaining challenge is to construct asymptotically good Pauli-LDPC codes with fully addressable transversal non-Clifford one-
qubit gates.
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Statistical Mechanics
Reference-Measure Freedom of the Effective Hamiltonian: From Stochastic Thermodynamics to the Macroscopic Limit
Ryuichi Okamoto
The effective
Hamiltonian (EH), also referred to as the potential of mean force or free-energy landscape, is widely used to describe
equilibrium properties and slow dynamics in chemical and soft-matter systems. However, the conventional EH has been argued to be ill-defined because it does not transform as a scalar under coordinate transformations. We identify an implicit change of reference measure (gauge), rather than the coordinate transformation itself, as the origin of this apparent problem. We formulate the EH as a scalar relative to a chosen gauge and derive the intrinsic, gauge-independent Fokker–Planck equation (FPE) on the
manifold of slow variables. The conventional EH and the
diffusion-dependent EH introduced in a Riemannian formulation, together with their corresponding FPEs, are thus different gauge representations of the same
equilibrium measure and intrinsic
stochastic dynamics. We further demonstrate that the gauge choice has an operational meaning: different restraint protocols select different reference measures. In the macroscopic limit, the leading EH becomes gauge independent within a class of subleading gauges and is determined by the large-deviation rate function. In the same limit, the
stochastic dynamics reduces to gauge-independent deterministic dynamics.
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General Relativity and Quantum Cosmology
RRR fluctuations from non-singular bounce
Sayantan Choudhury
We present a consistent treatment of regularization, renormalization, and resummation in a framework involving a contracting phase, a non-singular bounce, and inflation with a sharp transition from slow-roll to ultra-slow-roll, enabling
primordial black hole production. Within an effective field theory approach, we compute
quantum loop corrections to the power spectrum across all phases. Quadratic UV divergences are removed through renormalization, while logarithmic IR divergences are softened via resummation, demonstrating scheme independence. The inclusion of contraction and bounce allows the generation of
solar-mass PBHs, $M_{\rm PBH}\sim{\cal O}(M_\odot)$, with minimal inflation $\Delta N_{\rm Total}\sim{\cal O}(60)$, thereby evading the no-go
theorem. For $0.88\le c_s\le1$, the peak spectrum amplitude lies within $10^{-3}\le A\le10^{-2}$, preserving causality and unitarity. PBH abundances across $10^{-33}\!-\!10^{-27}$ and $10^{-6}\!-\!10^{-1}M_\odot$ are confronted with microlensing constraints to control PBH overproduction.
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Quantum Physics
Quantum Pseudorandom Error-Correcting Codes
Min-Hsiu Hsieh and Shogo Yamada
Pseudorandom error-correcting codes (PRCs), introduced by Christ and Gunn [CRYPTO 2024], are classical error-correcting codes whose codewords are computationally indistinguishable from uniformly random strings. We initiate the study of
quantum analogues of PRCs. We define
quantum pseudorandom error-correcting codes (QPRCs). Assuming that Learning Parity with Noise (LPN) is hard for $2^{O(\sqrt{n})}$-time
quantum algorithms, we construct QPRCs whose encodings are indistinguishable from Haar-random isometries. We call these pseudorandom isometric error-correcting codes (PRICs), and our construction is robust to all $o(n \frac{\log \log n}{\log n})$-local
quantum noise, where $n$ is the number of physical
qubits. Under the same assumption, we also construct QPRCs whose encodings are indistinguishable from the completely depolarizing channel and that are robust to all $\alpha n$-local
quantum noise for some constant $\alpha>0$. The latter QPRCs give a direct
quantum analogue of classical PRCs. To construct PRICs, we develop two technical ingredients of independent interest. First, we introduce a new classical cryptographic primitive which we call pseudorandom functional error-correcting codes (PRFCs) and construct them under the same LPN assumption. Second, we develop a new efficient decoding procedure within the codeword-stabilized (CWS) framework introduced in [Cross, Smith, Smolin, and Zeng, IEEE ISIT 2008], which is a generic framework for constructing
quantum error-correcting codes by combining (possibly nonlinear) classical error-correcting codes and graphs. This resolves the open problem of finding a general method for efficiently decoding such CWS codes based on nonlinear classical codes, raised in [Li, Dumer, Grassl, and Pryadko, Physical Review A 2010].
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